The present invention relates generally to the art of signal processors, and more specifically concerns a system for sorting, according to source, pulsed signals originated by a plurality of sources and received at two or more physically separated receivers.
Among other advantages, signals which have been sorted according to source may be further processed to provide information as to the physical location of the sources.
In a particular application, the physical area of interest may include several thousand emitters having various carrier pulse repetition frequencies. Initially known filtering techniques are frequently used in the art to reduce the number of signals to be processed to a particular frequency range. These techniques include band-pass filtering, centered around a selected carrier and/or pulse repetition frequency, and spatial angle of arrival filtering. These filtering techniques reduce the total number of received signals to a more manageable level, and limit further signal processing to only those signals of interest, but do not accomplish signal sorting according to source.
The prior art source-sorting techniques can be generally divided into two basic categories; real time and non-real time. Non-real time processing, which is usually accomplished with a computer, is advantageous in those instances where there is sufficient time between the receipt of the signals and the time at which the resulting information is required to accomplish the required computer processing routines. However, all non-real time processors have the significant disadvantage of being too slow when the sorting information is required real-time. In such instances, the sorting information provided by non-real time processors is often useless by the time it is ready, because changing circumstances have made it out-of-date.
Hence, real time processing is necessary in many applications. Existing real time processors for sorting received signals according to source, however, require complex and expensive hardware. In addition, the processing routines tend to be lengthy and complicated to achieve accurate results. The time resolution of the processing computations is thus made relatively low and the results are consequently often inaccurate and/or unreliable. Hence, real-time processors are infrequently used.
Accordingly, it is an object of the present invention to provide an apparatus and a process which eliminates one or more of the problems of the prior art discussed above.
It is another object of the present invention to provide such an apparatus/process which is capable of accurately sorting, in real time, signals received by two or more spaced receivers according to source.
It is a further object of the present invention to provide such an apparatus/process which is capable of sorting received signals according to source using only time of arrival data.
It is an additional object of the present invention to provide such an apparatus/process which provides accurate results due to the high time resolution of its computations.
It is an additional object of the present invention to provide such an apparatus/process which is capable of modifying its sorting techniques in accordance with additional information concerning the received signals.
It is a still further object of the present invention to reduce the complexity and expense of existing real-time signal sorting systems.